Look through this superior resource FIRST and FOREMOST: So you want to learn a language
Consider anything else on this page extra.
General Tools & ReferencesEdit
http://fsi-language-courses.org/Content.php - Features courses developed by the US government which are now in the public domain.
http://www.byki.com/fls/FLS.html - Freeware version of flashcard software, has sets of free lists for various languages as well as lists created by the community that are available for free as well. Email required.
http://www.forvo.com/ - Community content driven site where you can listen to a native speaker pronounce a word or phrase, or add one to be pronounced if it's not currently uploaded.
http://www.youtube.com/user/ProfASAr - Excellent channel on Languages by a good professor.
http://www.memrise.com/ - Excellent resource to learn vocabulary.
There are many torrents available that bundle resources to learn a language. Listed below are only a few of them. I recommend looking through the usual places yourself because there may be other torrents more suitable for your needs.
25 Language Learning Packs Collection [torrent]
Japanese Language Learning Pack [torrent]
Generally, the most common reason a foreigner wants to learn Arabic is to be able to read the Qu'ran, so a lot of these websites have religious overtones, their lessons are still perfectly valid, so just ignore the religion, if you don't want it there, and learn Arabic.
All these links are for Mandarin Chinese, the "standard Chinese", there are dozens of mutually unintelligible Chinese dialects that are not represented by this list
For those /sci/entists without a full grasp of the language
http://www.vocabulary.com/ Just awesome site for vocabulary
http://freerice.com/#/english-vocabulary/ Another site (and rice gathering)
Hindi is pluricentric, which means there is more than one standard form, "Hindi" and "Urdu", they are both very very similar, with Hindi being more 'Sanskritic' and Urdu being closer to Arabic and Persian.
http://www.amazon.com/Teach-Yourself-Hindi-Complete-Course/dp/0071420126Teach Yourself Hindi: By Rupert Snell. Excellent Intro to the Hindi Language, one of the better books by TY. This is widely used as well so if you try to get help on a forum or something, chances are they have access to this very book.
http://www.omniglot.com/writing/urdu.htmAt the basic level, Urdu and Hindi are pretty much the same. Both vocabulary and grammar wise. The real difference only becomes apparent when one tries to read/write, or when the language is spoken/written in more formal situations, such as News Broadcasting, Poetry, Literature, Religious text. Urdu is written in a Perso-Arabic script called Nastaliq (اردو )which is a fancy cursive version of that linear Arabic people often see. Hindi on the other hand is written in Devanagari (हिंदी ).
http://www.amazon.com/Read-Write-Urdu-Script-Reference/dp/007174746X/ref=dp_ob_title_bk/188-4845982-5986639Teach Yourself Beginner's Urdu Script: Probably THE go to book for learning how to read and write the Urdu Script. The writer does not assume the learner has any previous knowledge of the script/language, so this is pretty much Babby's First Urdu Book. Pretty much hovers around the $10 range.
http://www.amazon.com/Urdu-Essential-Grammar-Grammars/dp/0415163811/ref=sr_1_1?s=books&ie=UTF8&qid=1326605330&sr=1-1Urdu: An essential grammar: THE Grammar guide for the serious student. A bit pricey but a better Urdu Grammar Guide in English does not exist.
http://www.jisho.org/ Japenses-English Dictionary
Portuguese proper, rather than Brazilian Portuguese, though they are mutually intelligible, so it doesn't really matter which you learn
Punjabi is a North Indian/Pakistani language. Punjabi is mainly written in two scripts, Gurmukhi (Similar to the script used to write Hindi, Devanagari) and Shahmukhi (Perso-Arabic Script written in the calligraphic style known as Nastaliq. Think Persian/Farsi). The former is the script used in the Indian side of Punjab, while the latter is the script of choice in the Pakistan side of Punjab. At current there are no guides worth noting for learning Shahmukhi available in English, so a guide for learning to read and write Urdu will suffice, as Urdu and Punjabi both use almost exactly the same script.
A website run by the Punjabi University, Patiala. This particular university is well known for putting out most of the available resources for learning the Punjabi Language, so if you pick up a book to learn Punjabi, there's a good chance it probably came from this University. This website has a pretty solid introduction to the Punjabi Language, but it is by no means an end all be all resource for learning.
A less in dept version of the Punjabi University Patiala website. Has audio files attached for learning the Gurmukhi Script though, which is quite helpful for those not familiar with the sounds of Indo-European languages.
http://www.apnaorg.com/ As far as online media goes, this place is the Holy Grail. Hosts music, movies, books, poetry, etc, etc. Very useful tool for those learners of the language who are looking in building vocabulary through immersion.
http://forum.wordreference.com/forumdisplay.php?f=99 Sub-Section of a language learning forum, this particular section focuses on Indo-European Languages. The community here can often provide insight into some of the nitty-gritty details of the language that no one ever talks about.
http://www.youtube.com/playlist?list=PLF2F566484C119BF4&feature=plcp - Russian lessons originally designed for distance learning in high school.
http://www.memrise.com/ - Very good with vocabulary, presents vocabulary as nominative case.
http://2ch.hk/ - Russian Chan